In popular American history, the decades between the founding era and the Civil War are a sort of no-man’s land, largely glossed over if not ignored entirely. There are, of course, exceptions. Daniel Walker Howe explored the richness of the period in “What Hath God Wrought” and won the Pulitzer Prize for his trouble. Andrew Jackson commands a new volume with some regularity. Mostly, though, the era is treated as a dreary interregnum between those plucky patriots with powdered hair and the appalling carnage of the war over slavery.

In “Snow-Storm in August,” former Washington Post reporter Jefferson Morley fills in some of the blanks, assembling a portrait of Washington in the 1830s by exploring characters who inhabit the second tier of history or well below. The plunge beneath the surface of history exposes realities more true to daily experience than executive proclamations or speeches in Congress.

The book’s central motif is race, and the theme reverberates through a range of fascinating vignettes. Beverly Snow, an enterprising mulatto slave in Lynchburg, Va., is freed by his owners and reinvents himself as a leading restaurateur in the nation’s capital. Nat Turner’s bloody slave rising in Virginia triggers a nationwide spasm of fear. The American Colonization Society blindly pursues its mad scheme of shipping millions of freed slaves to Africa, or the Caribbean, or anywhere but the United States.

Perhaps most tantalizingly, the wealthy Tappan brothers of New York bankroll a pamphlet campaign that blankets the South with a million denunciations of human bondage, provoking howls of rage from slaveholders.

In fitful appearances in the narrative, Francis Scott Key of Maryland turns out to have had an eventful legal career after writing the lyrics for “The Star-Spangled Banner” in 1814. He defends former Tennessee governorSam Houston, who has viciously caned an Ohio congressman for alleging Houston’s involvement in public corruption. Key supports the rise of his brother-in-law, Roger Taney, who will become President Jackson’s appointee as chief justice of the Supreme Court. Though he frees two of his seven slaves, Key tenaciously defends segregation and slavery as the chief prosecutor in the District of Columbia.

The hinge of the book is the story of Arthur Bowen, a discontented teenage slave in the household of Anna Thornton, widow of the multi-talented William Thornton, who designed the U.S. Capitol building. After a night of drinking, Bowen, axe in hand, stumbles into a bedroom where three women are sleeping. When Anna Thornton sounds the alarm, Bowen flees. Upon Bowen’s arrest, white Washingtonians take to the streets in a not-too-bloody rampage, to which Key responds by prosecuting both Bowen and the ringleaders of the riot. Even slave-owning Jackson takes a turn onstage near the end of the saga.

To build this sprawling tale, Morley draws on marvelous sources. Anna Thornton’s diary provides an intimate personal account of key events. Morley effectively employs trial transcripts, D.C. property records and even newspaper advertisements. Yet the story moves laterally almost as much as it moves forward. Through the first third of the book, readers must trust that a narrative thrust will emerge — and it will.

Readers may find two elements of the book jarring, beginning with the assertion that pro-slavery and anti-slavery forces in the 1830s resembled today’s political division between “red” (conservative) and “blue” (liberal). The anachronism is unhelpful at best, misleading at worst. And the narrative sometimes purports to explore the inner thoughts of characters without citing any source. Examples include Bowen’s reaction to the death of William Thornton (he “felt the loss as much as anyone”) and his drunken perception, as he stands outside Anna Thornton’s room holding his axe, that “the house was tilting like a steamship.” Perhaps there are sources for these interior observations, but neither the text nor the notes reveal them.

As an exploration of America’s capital city at a time when the fault line over slavery had become impossible to ignore, “Snow-Storm in August” deepens our appreciation of how slavery made a mockery of the founding and made the Civil War as close to inevitable as any event in our history.

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Comments our editors find particularly useful or relevant are displayed in Top Comments, as are comments by users with these badges: . Replies to those posts appear here, as well as posts by staff writers.